Eggrobo

Eggrobo is a badnik that appears in Sky Sanctuary Zone in Sonic and Knuckles. He is shaped like an egg with arms and legs (clearly made to resemble Dr. Eggman), and attacks Sonic with a laser pistol. An Eggrobo also pilots the eggpods during boss sequences when you play as Knuckles. This is because Knuckles is unaware that Eggman is the real villain, so Eggrobo is used as a stand-in.

Eggrobo is also a hidden character in Sonic R. He appears when you collect all the gold coins in Reactive Factory.